CHEM 1120 1st Edition Lecture 6 Outline of last lecture 1 Chemical kinetics 2 Factors that affect reaction rates 3 Types of rates measured 4 Average rates and plotting data gathering information from plotted data 5 Concentration and Rate Laws Outline of Current Lecture 1 Finish up last lectures 14 3 2 Change of concentration with time 3 First order reactions 4 Second order reactions 5 Zeroth order reactions Current Lecture Chapter 14 Chemical Kinetics Continued Strategy for Determining Rate Law using initial rates o Rate laws must be determined experimentally o Method of initial rates Determines reaction orders from the effect of changing a reactants concentration on initial rate of reaction These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute o Rate k A m B n Our strategy is to systematically vary the concentrations of A and B o Refer to slides 28 31 on the Chapter 14 Powerpoint for examples and detailed explanations on this strategy 14 4 The change of concentration with time concentration and time equations are derived using calculus resulting equations depend on rate law used called integrated rate laws o First order reaction Integrated rate law next page Variables Logarithm review Refer to slides 34 through 38 and on Chapter 14 Powerpoint for detailed explanations on two example problems for first order reactions as well as picture detailed explanations how to determine reaction order and rate constant k o Second order reactions 1 A t k t 1 A o same structure as y mx b On a graph if linear it will be 2nd order reaction o Zeroth Order Rate Law A t kt A o or y mx b Summary of first second and zeroth reaction order and rates Zero order First order Second order Rate law Rate k Rate k A Rate k A Units for k mol L s 1 s L mol s Integrated rate law in straightline form A kt A t ln A k t t ln A 0 1 A k t 1 t A 0 Plot for straight line A vs t t ln A vs t t 1 A vs t t Slope y intercept k A 0 k ln A k 1 A Half life A 2k 0 ln 2 k 0 1 k A 0 0